Dept. of Entomology

EFFECTIVENESS OF NEWER CHEMISTRY INSECTICIDES AGAINST CITRUS LEAFMINER (Phyllocnistis citrella) INFESTING JARA LEMON IN SYLHET REGION

2025-08-24T09:15:20Z

EFFECTIVENESS OF NEWER CHEMISTRY INSECTICIDES AGAINST CITRUS LEAFMINER (Phyllocnistis citrella) INFESTING JARA LEMON IN SYLHET REGION NANDI, MOHON The study on the effectiveness of newer chemistry insecticides against Citrus leafminer (Phyllocnistis citrella) was conducted in the farmer’s Jara lemon field at Bagerkhal under Fatehpur Union, Jaintapur Upazilla, Sylhet during January to August, 2016. The insecticide treatments were imidacloprid (Sapta 70 WG) (T1) applied at 0.5 g L-1 of water, bioneem plus (Azadirachtin 1 EC) (T2) applied at 1 ml L-1 of water, spinosad (Tracer 45 SC) (T3) applied at 1.25 ml L-1 of water, chlorfenapyr (Intrepid 10 SC) (T4) applied at 1 ml L-1 of water and untreated control (T5) with four replications. The treatments were randomly assigned to each replication and applied at 20-day intervals. Data of leaf infestation were collected from four canopies of one tagged plant. Each of four canopies was selected respectively from north, east, west and south direction of the tagged plant. The numbers of infested leaves were counted at 20-day intervals. The infestation rate was calculated from the mean data of four replicates for each treatment. The results revealed that highest leaf infestation reduction (22%) was obtained from the plant treated with bioneem plus (Azadirachtin 1 EC) (T2) followed by spinosad (Tracer 45 SC) (T3) (29.25%). The results indicate that bioneem plus and spinosad are most effective for the management of leafminer infesting Jara lemon. Bioneem plus treated plants offered highest fruit yield of Jara lemon (1.82 t ha-1), closely followed by spinosad (1.71 t ha-1). As regard to economic analysis, the highest Marginal Benefit Cost Ratio (MBCR) (9.55) was obtained from the treatment bioneem plus (T2), closely followed by spinosad (T3) (8.21). Based on crop protection level and economic returns, bioneem plus and spinosad may be recommended for the management of leafminer in Jara lemon.

DETERMINATION OF EFFECTIVE DOSE OF CLOVE POWDER FOR THE MANAGEMENT OF PULSE BEETLE (Callosobruchus chinensis L.) INFESTING CHICKPEA AT LABORATORY CONDITION

2025-08-13T09:46:01Z

DETERMINATION OF EFFECTIVE DOSE OF CLOVE POWDER FOR THE MANAGEMENT OF PULSE BEETLE (Callosobruchus chinensis L.) INFESTING CHICKPEA AT LABORATORY CONDITION DEBNATH, RONI A study was conducted to determine the effective lower dose(s) of clove powder against the pulse beetle, Callosobruchus chinensis L. on chickpea seeds kept in Petri Dishes, Laboratory of Entomology, Sylhet Agricultural University, Sylhet during the period from April to August, 2016. The effectiveness of different doses of clove powder as seed protectant was assessed at 1, 3, 5, 7, 9, 11 and 13 g kg-1 of chickpea seeds on the basis of adult mortality (%), total number of eggs laid (egg laying capacity), adult emergence (%) and seed weight loss (%) caused by the pulse beetle. Clove powder treated seeds did not host any egg on their surface and no adult was emerged when they were treated with 9, 11 and 13 g kg-1 of chickpea seeds. Seed weight loss was lowest (0.00%) at 11 and 13 g kg-1 of chickpea seeds, whereas the highest adult mortality (100%) was recorded at 9 and 13 g kg-1 of chickpea seeds. In contrast, control seeds had maximum number of eggs laid (229.67), adult emergence (77.86%) and seed weight loss (30.38%) with the minimum adult mortality of 6.7%. It was found that total number of eggs laid, adult emergence (%) and seed weight loss (%) were markedly reduced whereas adult mortality increased with increasing the doses of clove powder as seed protectant.

DEVELOPMENT OF EFFECTIVE MANAGEMENT PRACTICES AGAINST POD BORER (Helicoverpa armigera Hubner) IN CHICKPEA

2025-08-13T09:37:23Z

DEVELOPMENT OF EFFECTIVE MANAGEMENT PRACTICES AGAINST POD BORER (Helicoverpa armigera Hubner) IN CHICKPEA ALAM, SANJIDA The study was conducted to develop effective management practices against chickpea pod borer in the research field of Plant Pathology and Seed Science Department, Faculty of Agriculture, Sylhet Agricultural University (SAU), Sylhet from 25 November, 2014 to15 April, 2015. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. There were seven treatments including synthetic insecticides and botanicals. The treatments were lamda-chyhalothrin (Karate 2.5EC) applied @ 1.5 ml/L of water (T1), chloropyriphos + cypermethrin (Nitro 505EC) applied @ 2 ml/L of water (T2), chlorantranilprole + thiamethoxam (Virtako 40WG) applied @ 0.15g/L of water (T3), neem leaf extract (1:4) (T4), biskatali leaf extract (1:4) (T5), marigold leaf extract (1:4) (T6) and control (untreated) (T7). The 1st spray was applied at 50% of flowering stage, 2nd and 3rd sprays were applied at 10-day intervals after the 1st spray. Data on pod damage (%), reduction of pod damage over control (%) and seed yield (t ha-1) was recorded and analyzed statistically. Significant variations in pod damage and seed yield were observed among different treatments. The highest pod damage reduction (72.53%) over control was found from the plots treated with lamdachyhalothrin. The highest seed yield (1.6 t ha-1) and highest Marginal Benefit Cost Ratio (MBCR) (4.60) was also obtained from the same plots treated with lamda-chyhalothrin (T1). The 2nd highest MBCR (3.77) was found from the plots that were treated with neem leaf extract (T4). The results indicate that the use of lamda-chyhalothrin @ 1.5 ml/L of water is biologically effective and economically viable followed by neem leaf extract for the management of chickpea pod borer.

DETERMINATION OF PEST STATUS, DISTRIBUTION, HOST PREFERENCE AND SEASONAL ABUNDANCE OF MAJOR INSECT PESTS OF CITRUS IN SYLHET

2025-02-16T10:34:27Z

DETERMINATION OF PEST STATUS, DISTRIBUTION, HOST PREFERENCE AND SEASONAL ABUNDANCE OF MAJOR INSECT PESTS OF CITRUS IN SYLHET BHUIYAN, MD. ARAFATH HOSSAIN LITON The study was conducted to determine the pest status, spatio-temporal distribution and host preference of major insect pests of citrus at Jaintapur, Sylhet during May to October 2014. Three type citrus orchards viz. Mandarin, Sweet orange and Jara lebu were selected randomly from five locations viz. Citrus Research Station, Dowdic, Bagerkhal, Lamashampur and Utlarpar of two Unions viz. Nijpat and Fatehpur in Jaintapur, Sylhet. In each location, four plants were tagged randomly and five canopy directions of each plant viz. north, south, east, west and central were considered from the middle canopy of the plant. One twig from each canopy direction was selected randomly and infested leaves were counted at 21days interval from 50 leaves of the selected twig and infested fruits were also counted from 25 fruits of each canopy direction. Insect pest status, distribution, host preference and seasonal abundance of major insect pests were determined on the basis of leaf and fruit infestation (%). Insects were considered major pests when leaf infestation reached to 30% or >30% and when fruit infestation reached to 25 or >25%. Insects were considered minor pests when leaf and fruit infestation was <30% and <25% respectively. A total of 13 insect pests were found to attack Mandarin, Sweet orange and Jara lebu at Jaintapur, Sylhet. Among them 5 species viz. Lemon butterfly, Citrus leafminer, Asian citrus psyllid, Citrus red mite and Spined citrus bug were found as major pests. The average leaf infestation (Mean±SD) was 37.44±3.07% for Lemon butterfly, 55.36±2.99% for Citrus leaf miner, 52.62±2.34% and 60.40±1.97% for Asian citrus psyllid and Citrus red mite respectively. Besides, the average fruit infestation (Mean±SD) was 29.95±1.35% for Citrus red mite and 34.63±3.00% for Spined citrus bug. The distribution of major insect pests on both leaves and fruits were almost similar across the study sites, but the canopy directions had significant influence on the abundance of major insect pests. The maximum average leaf infestation (45.18±3.66%) by Lemon butterfly was found in north canopy and minimum (32.44±2.19%) in south canopy. The maximum average leaf infestation (64.70±3.38%) by Citrus leaf miner was found in north canopy and minimum (49.12±2.13%) in east canopy. The maximum average leaf infestation (60.88±2.45%) caused by Asian citrus psyllid was found in north canopy and minimum (47.92±2.22%) in east canopy. The maximum average leaf infestation (64.48±2.46 %) by Citrus red mite was found in north canopy and minimum (53.90 ± 1.82 %) in central canopy. The maximum average fruit infestation (45.96±1.86%) and (39.28±1.41%) by Citrus red mite was found on Jara lebu and Mandarin respectively in north canopy, while maximum (34.04±1.08%) fruit infestation on Sweet orange was found in east canopy. The minimum average fruit infestation (22.68±0.94%), (16.16±1.17%) and (20.44±0.80%) by Citrus red mite was found on Jara lebu, Mandarin and Sweet orange respectively in central canopy. The maximum average fruit infestation (28.44±3.87%) and (54.92±4.08%) by Spined citrus bug was found on Jara lebu and Mandarin respectively in north canopy, while maximum (44.28±3.50%) fruit infestation on Sweet orange was found in east canopy. The minimum average fruit infestation (10.76±1.90%), (31.92±2.73%) and (27.56±2.56%) by Spined citrus bug was found on Jara lebu, Mandarin and Sweet orange respectively in central canopy. Lemon butterfly preferred most (47.58±2.54%) the leaves of Sweet orange and least (20.78±4.52%) the leaves of Jara lebu. Citrus leaf miner preferred most (56.50±3.18 %) the leaves of Jara lebu and least (53.52±3.22%) the leaves of Mandarin. Asian citrus psyllid preferred most (58.46±1.82%) the leaves of Jara lebu and least (43.34±2.90%) the leaves of Mandarin. Citrus red mite preferred most (63.96±1.89%) the leaves of Jara lebu and least (57.48±1.74%) the leaves of Mandarin. Citrus red mite also preferred most (35.28±1.39%) the fruits of Jara lebu and least (27.16±1.43%) the Mandarin. Spined citrus bug preferred most (40.00±3.36%) the fruits of Mandarin and least (22.76±2.63%) the Jara lebu. The infestation of Lemon butterfly ranged from 30.06 to 42.56% during May to October 2014, with maximum (42.56±5.20%) during September to October and minimum (30.06±7.5%) in May. The infestation of Citrus leaf miner ranged from 52.00 to 61.80%, with maximum (61.80 ± 1.20%) in May and (61.80±1.11%) in October. The infestation of Citrus leaf miner was minimum (52.00±1.11%) in June. The infestation of Asian citrus psyllid ranged from 46.70 to 56.46%, with maximum (56.46±4.90%) in August and minimum (46.70±4.27%) in May. The infestation of Spined citrus bug ranged from 19.08 to 47.44%, with maximum (47.44±3.00 %) in September and minimum (19.08±1.77%) in May. In case of leaf, the infestation of Citrus red mite ranged from 59.40 to 64.30%, with maximum (64.30±1.98%) in September and minimum (59.40±2.20%) in July. In case of fruit, the infestation ranged from 31.04 to 35.04%, with maximum (35.04±1.03%) in May and minimum (31.04±1.25%) in July. Spatio-temporal distribution was closely related with temperature and relative humidity and flushes of new leaves as well as maturity of fruits. The host preference of Lemon butterfly ranked as Sweet orange>Mandarin>Jara lebu. On the other hand, the host preference of Citrus leaf miner, Asian citrus psyllid and Citrus red mite ranked as Jara lebu>Sweet orange>Mandarin. The host preference of Spined citrus bug ranked as Mandarin>Sweet orange>Jara lebu.